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Abstract

Glyoxylate cycle enzymes isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2) are synthesised during the terminal irreversible phase of cucumber cotyledon senescence when the endomembrane system (endoplasmic reticulum, Golgi and tonoplast) is disassembled. This follows the period of reversible senescence when most chloroplast thylakoid membrane disassembly occurs. During the terminal stage of senescence, nuclear integrity is maintained for gene transcription, and mitochondria and peroxisomes are thought to participate in reactions of the glyoxylate cycle and gluconeogenesis.